🎉 Initial commit: README notes on workflow file structure, icon color format, compatibility dialog

Fix dialog image

Author: sebj

README.md

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+# Shortcuts File Format
+Shortcuts are exported from the iOS 12 Shortcuts app with a `.shortcuts` extension. Workflows exported from the Workflows app use a `.wflow` extension, but share the same internal format.
+
+## File Structure
+The format of a shortcut and a workflow file are the same – the file format does not seem to have changed going from the Workflow app to Apple’s iOS 12 Shortcuts app. Many strings remain prefixed with `WFWorkflow`.
+
+The file is in a binary property list format. It’s possible to open it by transferring to a Mac and changing the file extension to `.plist`, where it can then be viewed in Xcode or other supported apps.
+
+* `WFWorkflowClientVersion`: A number representing the version of the client app used to create the workflow (e.g. 700).
+* `WFWorkflowClientRelease`: A string representing the release semantic version of the client app used to create the workflow (e.g. “1.7.8” or “2.0.0”)
+* `WFWorkflowMinimumClientVersion`: An optional string representing the minimum client app version required to run the workflow (e.g. 411)
+* `WFWorkflowName`: An optional string name for the workflow. If this is not present, an imported workflow’s filename will be used
+* `WFWorkflowIcon`: An object containing:
+	* `WFWorkflowIconStartColor`: A number representing color of the workflow’s icon, see below.
+	* `WFWorkflowIconImageData`: Data
+	* `WFWorkflowIconGlyphNumber`: A number
+* `WFWorkflowInputContentItemClasses`:
+* `WFWorkflowTypes`:  An array of strings, representing the available usage types of the workflow, one or more of: `ActionExtension` (“Show in Share Sheet”, `NCWidget`  (“Show in [Notification Center] Widget”) or  `WatchKit` (watch availability, supported in the old Workflow app & Shortcuts during some iOS 12 betas)
+* `WFWorkflowActions`: Array of actions, each in the format:
+	* `WFWorkflowActionIdentifier`: An action identifier string, formatted in reverse domain name notation, e.g. `is.workflow.actions.address`
+	* `WFWorkflowActionParameters`: Array of parameters [String | Number | Object], each an identifier and a value 
+
+### Workflow Icon Start Color
+A number representing the start color of the workflow’s icon gradient. As an example, converting the value 4282601983 reveals an 8-digit hex color in the format RRGGBBAA, FF4351FF.
+
+This seems to work for all colors tested, except for dark gray (255).
+
+Shortcuts does not appear to support custom icon colours when a workflow edited on a Mac is opened on iOS – the colour will instead default to gray.
+
+Colors available in Shortcuts and their respective values (liable to change):
+* Red: 4282601983
+* Dark Orange: 4251333119
+* Orange: 4271458815
+* Yellow: 4274264319
+* Green: 4292093695
+* Turquoise: 431817727
+* Cyan: 1440408063
+* Blue: 463140863
+* Navy: 946986751
+* Violet: 2071128575
+* Purple: 3679049983
+* Dark Gray: 255
+* Pink: 3980825855
+* Taupe: 3031607807
+* Gray: 2846468607
+
+### Importing with a  `WFWorkflowMinimumClientVersion` greater than the client version
+
+In Shortcuts, importing a file with a `WFWorkflowMinimumClientVersion` that is greater than the client version will result in a warning dialog, shown below. The imported file can be duplicated or deleted, but not edited or executed.
+
+![Shortcut Format Too New Dialog](Shortcut%20Format%20Too%20New%20Dialog.png)
+
+**Shortcut Format Too New**
+
+This shortcut cannot be opened because it was created on a newer version of the Shortcuts app.
+
+Update Shortcuts [opens App Store] | OK
+
+## Misc Notes
+* The last Workflow version was 1.7.8
+* The first Shortcuts version was 2.0.0